Dr. Vohnsen will present important aspects of retinal imaging and analysis and of how one can use phototonics and visual optical testing to explore the detailed structure and function of the eye fundus.

UCD School of Physics, Room 128 @ 6:00 pm. All welcome.

November 13, 2013

Public Lecture: Images in Science

Speaker: Prof. John D. Barrow FRS, University of Cambridge, UK

There is a visual culture in science and it is rapidly changing. This talk will address the role of pictures and images in the development of science. From the first graphs and illustrated books to Molscript; from the influence of the first pictures of spiral galaxies on Van Gogh's 'Starry Night' to the Hubble Space Telescope, and from the mushroom cloud of the atomic bomb to the intricacy of fractals, we explore the past impact of pictures in science and the growing influence of images on scientific research and popularisation today as a result of the IT revolution.

Prof. John Barrow FRS is the author of several best-selling, highly acclaimed books about modern developments in physics, astronomy, and mathematics, including The Book of Nothing, The Infinite Book, The Left Hand of Creation and One Hundred Essential Things You Didn't Know You Didn't Know. He is a cosmologist, theoretical physicist, and mathematician. His book 'Cosmic Imagery: Key Images in the History of Science' provides the context for this lecture.

The gamma-ray sky contains a wealth or information about known astrophysical sources, such as active galaxies, pulsars, supernova remnants, etc., as well as more exotic sources such as dark matter annihilation. In the case of extremely faint signals, the interpretation of data requires sophisticated theoretical modeling as well as new analysis and statistical techniques. I will discuss recent work on novel statistical methods that can be used to test the hypothesis of extremely faint signals such as pulsars, solar system bodies, as well as more exotic signals such as annihilating dark matter.

It is shown how the existing theory of the dynamic Kerr effect and nonlinear dielectric relaxation based on the noninertial Brownian rotation of noninteracting rigid dipolar particles may be generalized to take into account interparticle interactions using the Maier-Saupe mean field potential. The results available in simple closed form suggest that the frequency dependent nonlinear response provides a method of measuring the Kramers escape rate or in the analogous problems of magnetic relaxation of fine single domain ferromagnetic particles and nematic liquid crystals, the superparamagnetic relaxation time and the retardation factor.

Light, though our eyes, gives us the most direct means of observing the world. Using a microscope we can see many objects invisible to the naked eye, but even the microscope has its limitations: it is impossible with a conventional microscope to resolve anything smaller than the wavelength of light. Typically this sets a resolution limit of about 0.5 microns. To do better than this and to get inside the wavelength scientists have been seeking a deeper understanding of light and its component electric and magnetic fields. We can now give a theoretical prescription for the perfect lens that has no limits to resolution. I shall report on recent progress and describe some experiments that bring light to an intense focus very much smaller than the free space wavelength.